1. Field of the Invention
This invention relates to shaped charge liners, methods of their manufacture, and their use in shaped charge explosives and munitions.
2. Description of Prior Art
There exists today a class of explosives and munitions which are used to produce holes or indentations in a surface or target against which the explosive or munition is directed. These explosives are known as shaped charges and typically can be utilized to penetrate the armor plate of military vehicles such as tanks and ships, to penetrate concrete fortifications, to aid in the penetration of rock formations during mining and excavation operations, or to provide quick access openings during emergency rescue operations. The art of shaped charge explosives is some seventy years old, is detailed in foreign and domestic reports, and is indicated in shaped charge munitions made and used by many nations. Current art in shaped charge explosive design is exemplified by a cylindrically shaped explosive compound, one end of which has a conically shaped cavity, the other end of which has a detonator, and the outer cylindrical surface of which is confined by a cylindrical metal shell. Into the conical cavity is inserted a copper or aluminum cone called the liner of the shaped charge. Current practice in the fabrication of the metallic shaped charge liner is the use of coining and machining processes to achieve liners of the desired shape and dimension.
To facilitate understanding of the present invention it is helpful to describe the phenomena associated with shaped charge explosive detonation. Upon activation of the detonator, a detonation wave propagates through the explosive compound. The resulting compression wave, upon reaching the apex of the conical liner compresses and starts to move the material of the liner, first in the region of the apex, and then progressively the rest of the liner as the compression wave reaches the bottom of the conical liner. During the process of compression and resulting collapse of the liner, a jet, having high speed, is made of a portion of the liner material. It is the high speed jet material which is associated with target penetration. Not all of the liner material is contained in the high speed jet. Some of the liner material follows behind the jet at a lower speed.
One of the major objectives in shaped charge explosive design is to obtain as great a penetration depth and hole volume in the target as can be achieved for a given weight and diameter of explosive charge. Experience shows that performance of shaped charge explosives is determined in part by the shape, density and ductility of the liner material. Experiments show that performance of currently used shaped charge explosives is also directly related to the maintaining of close demensional tolerances on the liner, particularly the wall thickness of the liner.
The theory of shaped charge penetration shows that to improve the performance of shaped charges, it is required to use liner materials of high density, to increase the speed of the jet formed by the shaped charge, and to increase the length of the continuous portion of the shaped charge jet. Theoretically, it is desirable to have a liner material having a density greater than that of the target. For typical military targets the jet should consist of materials of high density such as steel or tungsten.